git.c

   1 #include "builtin.h"
   2 #include "cache.h"
   3 #include "exec_cmd.h"
   4 #include "help.h"
   5 #include "quote.h"
   6 #include "run-command.h"
   7 #include "commit.h"
   8
   9 const char git_usage_string[] =
  10         "git [--version] [--help] [-C <path>] [-c name=value]\n"
  11         "           [--exec-path[=<path>]] [--html-path] [--man-path] [--info-path]\n"
  12         "           [-p|--paginate|--no-pager] [--no-replace-objects] [--bare]\n"
  13         "           [--git-dir=<path>] [--work-tree=<path>] [--namespace=<name>]\n"
  14         "           <command> [<args>]";
  15
  16 const char git_more_info_string[] =
  17         N_("'git help -a' and 'git help -g' lists available subcommands and some\n"
  18            "concept guides. See 'git help <command>' or 'git help <concept>'\n"
  19            "to read about a specific subcommand or concept.");
  20
  21 static struct startup_info git_startup_info;
  22 static int use_pager = -1;
  23
  24 static void commit_pager_choice(void) {
  25         switch (use_pager) {
  26         case 0:
  27                 setenv("GIT_PAGER", "cat", 1);
  28                 break;
  29         case 1:
  30                 setup_pager();
  31                 break;
  32         default:
  33                 break;
  34         }
  35 }
  36
  37 static int handle_options(const char ***argv, int *argc, int *envchanged)
  38 {
  39         const char **orig_argv = *argv;
  40
  41         while (*argc > 0) {
  42                 const char *cmd = (*argv)[0];
  43                 if (cmd[0] != '-')
  44                         break;
  45
  46                 /*
  47                  * For legacy reasons, the "version" and "help"
  48                  * commands can be written with "--" prepended
  49                  * to make them look like flags.
  50                  */
  51                 if (!strcmp(cmd, "--help") || !strcmp(cmd, "--version"))
  52                         break;
  53
  54                 /*
  55                  * Check remaining flags.
  56                  */
  57                 if (!prefixcmp(cmd, "--exec-path")) {
  58                         cmd += 11;
  59                         if (*cmd == '=')
  60                                 git_set_argv_exec_path(cmd + 1);
  61                         else {
  62                                 puts(git_exec_path());
  63                                 exit(0);
  64                         }
  65                 } else if (!strcmp(cmd, "--html-path")) {
  66                         puts(system_path(GIT_HTML_PATH));
  67                         exit(0);
  68                 } else if (!strcmp(cmd, "--man-path")) {
  69                         puts(system_path(GIT_MAN_PATH));
  70                         exit(0);
  71                 } else if (!strcmp(cmd, "--info-path")) {
  72                         puts(system_path(GIT_INFO_PATH));
  73                         exit(0);
  74                 } else if (!strcmp(cmd, "-p") || !strcmp(cmd, "--paginate")) {
  75                         use_pager = 1;
  76                 } else if (!strcmp(cmd, "--no-pager")) {
  77                         use_pager = 0;
  78                         if (envchanged)
  79                                 *envchanged = 1;
  80                 } else if (!strcmp(cmd, "--no-replace-objects")) {
  81                         read_replace_refs = 0;
  82                         setenv(NO_REPLACE_OBJECTS_ENVIRONMENT, "1", 1);
  83                         if (envchanged)
  84                                 *envchanged = 1;
  85                 } else if (!strcmp(cmd, "--git-dir")) {
  86                         if (*argc < 2) {
  87                                 fprintf(stderr, "No directory given for --git-dir.\n" );
  88                                 usage(git_usage_string);
  89                         }
  90                         setenv(GIT_DIR_ENVIRONMENT, (*argv)[1], 1);
  91                         if (envchanged)
  92                                 *envchanged = 1;
  93                         (*argv)++;
  94                         (*argc)--;
  95                 } else if (!prefixcmp(cmd, "--git-dir=")) {
  96                         setenv(GIT_DIR_ENVIRONMENT, cmd + 10, 1);
  97                         if (envchanged)
  98                                 *envchanged = 1;
  99                 } else if (!strcmp(cmd, "--namespace")) {
 100                         if (*argc < 2) {
 101                                 fprintf(stderr, "No namespace given for --namespace.\n" );
 102                                 usage(git_usage_string);
 103                         }
 104                         setenv(GIT_NAMESPACE_ENVIRONMENT, (*argv)[1], 1);
 105                         if (envchanged)
 106                                 *envchanged = 1;
 107                         (*argv)++;
 108                         (*argc)--;
 109                 } else if (!prefixcmp(cmd, "--namespace=")) {
 110                         setenv(GIT_NAMESPACE_ENVIRONMENT, cmd + 12, 1);
 111                         if (envchanged)
 112                                 *envchanged = 1;
 113                 } else if (!strcmp(cmd, "--work-tree")) {
 114                         if (*argc < 2) {
 115                                 fprintf(stderr, "No directory given for --work-tree.\n" );
 116                                 usage(git_usage_string);
 117                         }
 118                         setenv(GIT_WORK_TREE_ENVIRONMENT, (*argv)[1], 1);
 119                         if (envchanged)
 120                                 *envchanged = 1;
 121                         (*argv)++;
 122                         (*argc)--;
 123                 } else if (!prefixcmp(cmd, "--work-tree=")) {
 124                         setenv(GIT_WORK_TREE_ENVIRONMENT, cmd + 12, 1);
 125                         if (envchanged)
 126                                 *envchanged = 1;
 127                 } else if (!strcmp(cmd, "--bare")) {
 128                         static char git_dir[PATH_MAX+1];
 129                         is_bare_repository_cfg = 1;
 130                         setenv(GIT_DIR_ENVIRONMENT, getcwd(git_dir, sizeof(git_dir)), 0);
 131                         setenv(GIT_IMPLICIT_WORK_TREE_ENVIRONMENT, "0", 1);
 132                         if (envchanged)
 133                                 *envchanged = 1;
 134                 } else if (!strcmp(cmd, "-c")) {
 135                         if (*argc < 2) {
 136                                 fprintf(stderr, "-c expects a configuration string\n" );
 137                                 usage(git_usage_string);
 138                         }
 139                         git_config_push_parameter((*argv)[1]);
 140                         (*argv)++;
 141                         (*argc)--;
 142                 } else if (!strcmp(cmd, "--literal-pathspecs")) {
 143                         setenv(GIT_LITERAL_PATHSPECS_ENVIRONMENT, "1", 1);
 144                         if (envchanged)
 145                                 *envchanged = 1;
 146                 } else if (!strcmp(cmd, "--no-literal-pathspecs")) {
 147                         setenv(GIT_LITERAL_PATHSPECS_ENVIRONMENT, "0", 1);
 148                         if (envchanged)
 149                                 *envchanged = 1;
 150                 } else if (!strcmp(cmd, "--glob-pathspecs")) {
 151                         setenv(GIT_GLOB_PATHSPECS_ENVIRONMENT, "1", 1);
 152                         if (envchanged)
 153                                 *envchanged = 1;
 154                 } else if (!strcmp(cmd, "--noglob-pathspecs")) {
 155                         setenv(GIT_NOGLOB_PATHSPECS_ENVIRONMENT, "1", 1);
 156                         if (envchanged)
 157                                 *envchanged = 1;
 158                 } else if (!strcmp(cmd, "--icase-pathspecs")) {
 159                         setenv(GIT_ICASE_PATHSPECS_ENVIRONMENT, "1", 1);
 160                         if (envchanged)
 161                                 *envchanged = 1;
 162                 } else if (!strcmp(cmd, "--shallow-file")) {
 163                         (*argv)++;
 164                         (*argc)--;
 165                         set_alternate_shallow_file((*argv)[0]);
 166                         if (envchanged)
 167                                 *envchanged = 1;
 168                 } else if (!strcmp(cmd, "-C")) {
 169                         if (*argc < 2) {
 170                                 fprintf(stderr, "No directory given for -C.\n" );
 171                                 usage(git_usage_string);
 172                         }
 173                         if (chdir((*argv)[1]))
 174                                 die_errno("Cannot change to '%s'", (*argv)[1]);
 175                         if (envchanged)
 176                                 *envchanged = 1;
 177                         (*argv)++;
 178                         (*argc)--;
 179                 } else {
 180                         fprintf(stderr, "Unknown option: %s\n", cmd);
 181                         usage(git_usage_string);
 182                 }
 183
 184                 (*argv)++;
 185                 (*argc)--;
 186         }
 187         return (*argv) - orig_argv;
 188 }
 189
 190 static int handle_alias(int *argcp, const char ***argv)
 191 {
 192         int envchanged = 0, ret = 0, saved_errno = errno;
 193         const char *subdir;
 194         int count, option_count;
 195         const char **new_argv;
 196         const char *alias_command;
 197         char *alias_string;
 198         int unused_nongit;
 199
 200         subdir = setup_git_directory_gently(&unused_nongit);
 201
 202         alias_command = (*argv)[0];
 203         alias_string = alias_lookup(alias_command);
 204         if (alias_string) {
 205                 if (alias_string[0] == '!') {
 206                         const char **alias_argv;
 207                         int argc = *argcp, i;
 208
 209                         commit_pager_choice();
 210
 211                         /* build alias_argv */
 212                         alias_argv = xmalloc(sizeof(*alias_argv) * (argc + 1));
 213                         alias_argv[0] = alias_string + 1;
 214                         for (i = 1; i < argc; ++i)
 215                                 alias_argv[i] = (*argv)[i];
 216                         alias_argv[argc] = NULL;
 217
 218                         ret = run_command_v_opt(alias_argv, RUN_USING_SHELL);
 219                         if (ret >= 0)   /* normal exit */
 220                                 exit(ret);
 221
 222                         die_errno("While expanding alias '%s': '%s'",
 223                             alias_command, alias_string + 1);
 224                 }
 225                 count = split_cmdline(alias_string, &new_argv);
 226                 if (count < 0)
 227                         die("Bad alias.%s string: %s", alias_command,
 228                             split_cmdline_strerror(count));
 229                 option_count = handle_options(&new_argv, &count, &envchanged);
 230                 if (envchanged)
 231                         die("alias '%s' changes environment variables\n"
 232                                  "You can use '!git' in the alias to do this.",
 233                                  alias_command);
 234                 memmove(new_argv - option_count, new_argv,
 235                                 count * sizeof(char *));
 236                 new_argv -= option_count;
 237
 238                 if (count < 1)
 239                         die("empty alias for %s", alias_command);
 240
 241                 if (!strcmp(alias_command, new_argv[0]))
 242                         die("recursive alias: %s", alias_command);
 243
 244                 trace_argv_printf(new_argv,
 245                                   "trace: alias expansion: %s =>",
 246                                   alias_command);
 247
 248                 new_argv = xrealloc(new_argv, sizeof(char *) *
 249                                     (count + *argcp));
 250                 /* insert after command name */
 251                 memcpy(new_argv + count, *argv + 1, sizeof(char *) * *argcp);
 252
 253                 *argv = new_argv;
 254                 *argcp += count - 1;
 255
 256                 ret = 1;
 257         }
 258
 259         if (subdir && chdir(subdir))
 260                 die_errno("Cannot change to '%s'", subdir);
 261
 262         errno = saved_errno;
 263
 264         return ret;
 265 }
 266
 267 #define RUN_SETUP               (1<<0)
 268 #define RUN_SETUP_GENTLY        (1<<1)
 269 #define USE_PAGER               (1<<2)
 270 /*
 271  * require working tree to be present -- anything uses this needs
 272  * RUN_SETUP for reading from the configuration file.
 273  */
 274 #define NEED_WORK_TREE          (1<<3)
 275
 276 struct cmd_struct {
 277         const char *cmd;
 278         int (*fn)(int, const char **, const char *);
 279         int option;
 280 };
 281
 282 static int run_builtin(struct cmd_struct *p, int argc, const char **argv)
 283 {
 284         int status, help;
 285         struct stat st;
 286         const char *prefix;
 287
 288         prefix = NULL;
 289         help = argc == 2 && !strcmp(argv[1], "-h");
 290         if (!help) {
 291                 if (p->option & RUN_SETUP)
 292                         prefix = setup_git_directory();
 293                 if (p->option & RUN_SETUP_GENTLY) {
 294                         int nongit_ok;
 295                         prefix = setup_git_directory_gently(&nongit_ok);
 296                 }
 297
 298                 if (use_pager == -1 && p->option & (RUN_SETUP | RUN_SETUP_GENTLY))
 299                         use_pager = check_pager_config(p->cmd);
 300                 if (use_pager == -1 && p->option & USE_PAGER)
 301                         use_pager = 1;
 302
 303                 if ((p->option & (RUN_SETUP | RUN_SETUP_GENTLY)) &&
 304                     startup_info->have_repository) /* get_git_dir() may set up repo, avoid that */
 305                         trace_repo_setup(prefix);
 306         }
 307         commit_pager_choice();
 308
 309         if (!help && p->option & NEED_WORK_TREE)
 310                 setup_work_tree();
 311
 312         trace_argv_printf(argv, "trace: built-in: git");
 313
 314         status = p->fn(argc, argv, prefix);
 315         if (status)
 316                 return status;
 317
 318         /* Somebody closed stdout? */
 319         if (fstat(fileno(stdout), &st))
 320                 return 0;
 321         /* Ignore write errors for pipes and sockets.. */
 322         if (S_ISFIFO(st.st_mode) || S_ISSOCK(st.st_mode))
 323                 return 0;
 324
 325         /* Check for ENOSPC and EIO errors.. */
 326         if (fflush(stdout))
 327                 die_errno("write failure on standard output");
 328         if (ferror(stdout))
 329                 die("unknown write failure on standard output");
 330         if (fclose(stdout))
 331                 die_errno("close failed on standard output");
 332         return 0;
 333 }
 334
 335 static void handle_internal_command(int argc, const char **argv)
 336 {
 337         const char *cmd = argv[0];
 338         static struct cmd_struct commands[] = {
 339                 { "add", cmd_add, RUN_SETUP | NEED_WORK_TREE },
 340                 { "annotate", cmd_annotate, RUN_SETUP },
 341                 { "apply", cmd_apply, RUN_SETUP_GENTLY },
 342                 { "archive", cmd_archive },
 343                 { "bisect--helper", cmd_bisect__helper, RUN_SETUP },
 344                 { "blame", cmd_blame, RUN_SETUP },
 345                 { "branch", cmd_branch, RUN_SETUP },
 346                 { "bundle", cmd_bundle, RUN_SETUP_GENTLY },
 347                 { "cat-file", cmd_cat_file, RUN_SETUP },
 348                 { "check-attr", cmd_check_attr, RUN_SETUP },
 349                 { "check-ignore", cmd_check_ignore, RUN_SETUP | NEED_WORK_TREE },
 350                 { "check-mailmap", cmd_check_mailmap, RUN_SETUP },
 351                 { "check-ref-format", cmd_check_ref_format },
 352                 { "checkout", cmd_checkout, RUN_SETUP | NEED_WORK_TREE },
 353                 { "checkout-index", cmd_checkout_index,
 354                         RUN_SETUP | NEED_WORK_TREE},
 355                 { "cherry", cmd_cherry, RUN_SETUP },
 356                 { "cherry-pick", cmd_cherry_pick, RUN_SETUP | NEED_WORK_TREE },
 357                 { "clean", cmd_clean, RUN_SETUP | NEED_WORK_TREE },
 358                 { "clone", cmd_clone },
 359                 { "column", cmd_column, RUN_SETUP_GENTLY },
 360                 { "commit", cmd_commit, RUN_SETUP | NEED_WORK_TREE },
 361                 { "commit-tree", cmd_commit_tree, RUN_SETUP },
 362                 { "config", cmd_config, RUN_SETUP_GENTLY },
 363                 { "count-objects", cmd_count_objects, RUN_SETUP },
 364                 { "credential", cmd_credential, RUN_SETUP_GENTLY },
 365                 { "describe", cmd_describe, RUN_SETUP },
 366                 { "diff", cmd_diff },
 367                 { "diff-files", cmd_diff_files, RUN_SETUP | NEED_WORK_TREE },
 368                 { "diff-index", cmd_diff_index, RUN_SETUP },
 369                 { "diff-tree", cmd_diff_tree, RUN_SETUP },
 370                 { "fast-export", cmd_fast_export, RUN_SETUP },
 371                 { "fetch", cmd_fetch, RUN_SETUP },
 372                 { "fetch-pack", cmd_fetch_pack, RUN_SETUP },
 373                 { "fmt-merge-msg", cmd_fmt_merge_msg, RUN_SETUP },
 374                 { "for-each-ref", cmd_for_each_ref, RUN_SETUP },
 375                 { "format-patch", cmd_format_patch, RUN_SETUP },
 376                 { "fsck", cmd_fsck, RUN_SETUP },
 377                 { "fsck-objects", cmd_fsck, RUN_SETUP },
 378                 { "gc", cmd_gc, RUN_SETUP },
 379                 { "get-tar-commit-id", cmd_get_tar_commit_id },
 380                 { "grep", cmd_grep, RUN_SETUP_GENTLY },
 381                 { "hash-object", cmd_hash_object },
 382                 { "help", cmd_help },
 383                 { "index-pack", cmd_index_pack, RUN_SETUP_GENTLY },
 384                 { "init", cmd_init_db },
 385                 { "init-db", cmd_init_db },
 386                 { "log", cmd_log, RUN_SETUP },
 387                 { "ls-files", cmd_ls_files, RUN_SETUP },
 388                 { "ls-remote", cmd_ls_remote, RUN_SETUP_GENTLY },
 389                 { "ls-tree", cmd_ls_tree, RUN_SETUP },
 390                 { "mailinfo", cmd_mailinfo },
 391                 { "mailsplit", cmd_mailsplit },
 392                 { "merge", cmd_merge, RUN_SETUP | NEED_WORK_TREE },
 393                 { "merge-base", cmd_merge_base, RUN_SETUP },
 394                 { "merge-file", cmd_merge_file, RUN_SETUP_GENTLY },
 395                 { "merge-index", cmd_merge_index, RUN_SETUP },
 396                 { "merge-ours", cmd_merge_ours, RUN_SETUP },
 397                 { "merge-recursive", cmd_merge_recursive, RUN_SETUP | NEED_WORK_TREE },
 398                 { "merge-recursive-ours", cmd_merge_recursive, RUN_SETUP | NEED_WORK_TREE },
 399                 { "merge-recursive-theirs", cmd_merge_recursive, RUN_SETUP | NEED_WORK_TREE },
 400                 { "merge-subtree", cmd_merge_recursive, RUN_SETUP | NEED_WORK_TREE },
 401                 { "merge-tree", cmd_merge_tree, RUN_SETUP },
 402                 { "mktag", cmd_mktag, RUN_SETUP },
 403                 { "mktree", cmd_mktree, RUN_SETUP },
 404                 { "mv", cmd_mv, RUN_SETUP | NEED_WORK_TREE },
 405                 { "name-rev", cmd_name_rev, RUN_SETUP },
 406                 { "notes", cmd_notes, RUN_SETUP },
 407                 { "pack-objects", cmd_pack_objects, RUN_SETUP },
 408                 { "pack-redundant", cmd_pack_redundant, RUN_SETUP },
 409                 { "pack-refs", cmd_pack_refs, RUN_SETUP },
 410                 { "patch-id", cmd_patch_id },
 411                 { "peek-remote", cmd_ls_remote, RUN_SETUP_GENTLY },
 412                 { "pickaxe", cmd_blame, RUN_SETUP },
 413                 { "prune", cmd_prune, RUN_SETUP },
 414                 { "prune-packed", cmd_prune_packed, RUN_SETUP },
 415                 { "push", cmd_push, RUN_SETUP },
 416                 { "read-tree", cmd_read_tree, RUN_SETUP },
 417                 { "receive-pack", cmd_receive_pack },
 418                 { "reflog", cmd_reflog, RUN_SETUP },
 419                 { "remote", cmd_remote, RUN_SETUP },
 420                 { "remote-ext", cmd_remote_ext },
 421                 { "remote-fd", cmd_remote_fd },
 422                 { "repack", cmd_repack, RUN_SETUP },
 423                 { "replace", cmd_replace, RUN_SETUP },
 424                 { "repo-config", cmd_repo_config, RUN_SETUP_GENTLY },
 425                 { "rerere", cmd_rerere, RUN_SETUP },
 426                 { "reset", cmd_reset, RUN_SETUP },
 427                 { "rev-list", cmd_rev_list, RUN_SETUP },
 428                 { "rev-parse", cmd_rev_parse },
 429                 { "revert", cmd_revert, RUN_SETUP | NEED_WORK_TREE },
 430                 { "rm", cmd_rm, RUN_SETUP },
 431                 { "send-pack", cmd_send_pack, RUN_SETUP },
 432                 { "shortlog", cmd_shortlog, RUN_SETUP_GENTLY | USE_PAGER },
 433                 { "show", cmd_show, RUN_SETUP },
 434                 { "show-branch", cmd_show_branch, RUN_SETUP },
 435                 { "show-ref", cmd_show_ref, RUN_SETUP },
 436                 { "stage", cmd_add, RUN_SETUP | NEED_WORK_TREE },
 437                 { "status", cmd_status, RUN_SETUP | NEED_WORK_TREE },
 438                 { "stripspace", cmd_stripspace },
 439                 { "symbolic-ref", cmd_symbolic_ref, RUN_SETUP },
 440                 { "tag", cmd_tag, RUN_SETUP },
 441                 { "tar-tree", cmd_tar_tree },
 442                 { "unpack-file", cmd_unpack_file, RUN_SETUP },
 443                 { "unpack-objects", cmd_unpack_objects, RUN_SETUP },
 444                 { "update-index", cmd_update_index, RUN_SETUP },
 445                 { "update-ref", cmd_update_ref, RUN_SETUP },
 446                 { "update-server-info", cmd_update_server_info, RUN_SETUP },
 447                 { "upload-archive", cmd_upload_archive },
 448                 { "upload-archive--writer", cmd_upload_archive_writer },
 449                 { "var", cmd_var, RUN_SETUP_GENTLY },
 450                 { "verify-pack", cmd_verify_pack },
 451                 { "verify-tag", cmd_verify_tag, RUN_SETUP },
 452                 { "version", cmd_version },
 453                 { "whatchanged", cmd_whatchanged, RUN_SETUP },
 454                 { "write-tree", cmd_write_tree, RUN_SETUP },
 455         };
 456         int i;
 457         static const char ext[] = STRIP_EXTENSION;
 458
 459         if (sizeof(ext) > 1) {
 460                 i = strlen(argv[0]) - strlen(ext);
 461                 if (i > 0 && !strcmp(argv[0] + i, ext)) {
 462                         char *argv0 = xstrdup(argv[0]);
 463                         argv[0] = cmd = argv0;
 464                         argv0[i] = '\0';
 465                 }
 466         }
 467
 468         /* Turn "git cmd --help" into "git help cmd" */
 469         if (argc > 1 && !strcmp(argv[1], "--help")) {
 470                 argv[1] = argv[0];
 471                 argv[0] = cmd = "help";
 472         }
 473
 474         for (i = 0; i < ARRAY_SIZE(commands); i++) {
 475                 struct cmd_struct *p = commands+i;
 476                 if (strcmp(p->cmd, cmd))
 477                         continue;
 478                 exit(run_builtin(p, argc, argv));
 479         }
 480 }
 481
 482 static void execv_dashed_external(const char **argv)
 483 {
 484         struct strbuf cmd = STRBUF_INIT;
 485         const char *tmp;
 486         int status;
 487
 488         if (use_pager == -1)
 489                 use_pager = check_pager_config(argv[0]);
 490         commit_pager_choice();
 491
 492         strbuf_addf(&cmd, "git-%s", argv[0]);
 493
 494         /*
 495          * argv[0] must be the git command, but the argv array
 496          * belongs to the caller, and may be reused in
 497          * subsequent loop iterations. Save argv[0] and
 498          * restore it on error.
 499          */
 500         tmp = argv[0];
 501         argv[0] = cmd.buf;
 502
 503         trace_argv_printf(argv, "trace: exec:");
 504
 505         /*
 506          * if we fail because the command is not found, it is
 507          * OK to return. Otherwise, we just pass along the status code.
 508          */
 509         status = run_command_v_opt(argv, RUN_SILENT_EXEC_FAILURE | RUN_CLEAN_ON_EXIT);
 510         if (status >= 0 || errno != ENOENT)
 511                 exit(status);
 512
 513         argv[0] = tmp;
 514
 515         strbuf_release(&cmd);
 516 }
 517
 518 static int run_argv(int *argcp, const char ***argv)
 519 {
 520         int done_alias = 0;
 521
 522         while (1) {
 523                 /* See if it's an internal command */
 524                 handle_internal_command(*argcp, *argv);
 525
 526                 /* .. then try the external ones */
 527                 execv_dashed_external(*argv);
 528
 529                 /* It could be an alias -- this works around the insanity
 530                  * of overriding "git log" with "git show" by having
 531                  * alias.log = show
 532                  */
 533                 if (done_alias || !handle_alias(argcp, argv))
 534                         break;
 535                 done_alias = 1;
 536         }
 537
 538         return done_alias;
 539 }
 540
 541
 542 int main(int argc, char **av)
 543 {
 544         const char **argv = (const char **) av;
 545         const char *cmd;
 546
 547         startup_info = &git_startup_info;
 548
 549         cmd = git_extract_argv0_path(argv[0]);
 550         if (!cmd)
 551                 cmd = "git-help";
 552
 553         /*
 554          * Always open file descriptors 0/1/2 to avoid clobbering files
 555          * in die().  It also avoids messing up when the pipes are dup'ed
 556          * onto stdin/stdout/stderr in the child processes we spawn.
 557          */
 558         sanitize_stdfds();
 559
 560         git_setup_gettext();
 561
 562         /*
 563          * "git-xxxx" is the same as "git xxxx", but we obviously:
 564          *
 565          *  - cannot take flags in between the "git" and the "xxxx".
 566          *  - cannot execute it externally (since it would just do
 567          *    the same thing over again)
 568          *
 569          * So we just directly call the internal command handler, and
 570          * die if that one cannot handle it.
 571          */
 572         if (!prefixcmp(cmd, "git-")) {
 573                 cmd += 4;
 574                 argv[0] = cmd;
 575                 handle_internal_command(argc, argv);
 576                 die("cannot handle %s internally", cmd);
 577         }
 578
 579         /* Look for flags.. */
 580         argv++;
 581         argc--;
 582         handle_options(&argv, &argc, NULL);
 583         if (argc > 0) {
 584                 if (!prefixcmp(argv[0], "--"))
 585                         argv[0] += 2;
 586         } else {
 587                 /* The user didn't specify a command; give them help */
 588                 commit_pager_choice();
 589                 printf("usage: %s\n\n", git_usage_string);
 590                 list_common_cmds_help();
 591                 printf("\n%s\n", _(git_more_info_string));
 592                 exit(1);
 593         }
 594         cmd = argv[0];
 595
 596         /*
 597          * We use PATH to find git commands, but we prepend some higher
 598          * precedence paths: the "--exec-path" option, the GIT_EXEC_PATH
 599          * environment, and the $(gitexecdir) from the Makefile at build
 600          * time.
 601          */
 602         setup_path();
 603
 604         while (1) {
 605                 static int done_help = 0;
 606                 static int was_alias = 0;
 607                 was_alias = run_argv(&argc, &argv);
 608                 if (errno != ENOENT)
 609                         break;
 610                 if (was_alias) {
 611                         fprintf(stderr, "Expansion of alias '%s' failed; "
 612                                 "'%s' is not a git command\n",
 613                                 cmd, argv[0]);
 614                         exit(1);
 615                 }
 616                 if (!done_help) {
 617                         cmd = argv[0] = help_unknown_cmd(cmd);
 618                         done_help = 1;
 619                 } else
 620                         break;
 621         }
 622
 623         fprintf(stderr, "Failed to run command '%s': %s\n",
 624                 cmd, strerror(errno));
 625
 626         return 1;
 627 }